﻿/**************************************************************************\
    Copyright Microsoft Corporation. All Rights Reserved.
\**************************************************************************/

namespace Microsoft.Windows.Shell
{
	using System;
	using System.Collections.Generic;
	using System.Diagnostics.CodeAnalysis;
	using System.Reflection;
	using System.Runtime.InteropServices;
	using System.Security;
	using System.Security.Permissions;
	using System.Windows;
	using System.Windows.Interop;
	using System.Windows.Media;
	using System.Windows.Threading;
	using Standard;

	using HANDLE_MESSAGE = System.Collections.Generic.KeyValuePair<Standard.WM, Standard.MessageHandler>;

	internal class WindowChromeWorker : DependencyObject
	{
		private static readonly Version _presentationFrameworkVersion = Assembly.GetAssembly(typeof(Window)).GetName().Version;

		/// <summary>
		/// Is this using WPF4?
		/// </summary>
		/// <remarks>
		/// There are a few specific bugs in Window in 3.5SP1 and below that require workarounds
		/// when handling WM_NCCALCSIZE on the HWND.
		/// </remarks>
		private static bool IsPresentationFrameworkVersionLessThan4
		{
			get { return _presentationFrameworkVersion < new Version(4, 0); }
		}

		// Delegate signature used for Dispatcher.BeginInvoke.
		private delegate void _Action();

		#region Fields

		private const SWP _SwpFlags = SWP.FRAMECHANGED | SWP.NOSIZE | SWP.NOMOVE | SWP.NOZORDER | SWP.NOOWNERZORDER | SWP.NOACTIVATE;

		private readonly List<HANDLE_MESSAGE> _messageTable;

		/// <summary>The Window that's chrome is being modified.</summary>
		private Window _window;

		/// <summary>Underlying HWND for the _window.</summary>
		/// <SecurityNote>
		///   Critical : Critical member
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _hwnd;

		/// <summary>Underlying HWND for the _window.</summary>
		/// <SecurityNote>
		///   Critical : Critical member provides access to HWND's window messages which are critical
		/// </SecurityNote>
		[SecurityCritical]
		private HwndSource _hwndSource = null;

		private bool _isHooked = false;

		// These fields are for tracking workarounds for WPF 3.5SP1 behaviors.
		private bool _isFixedUp = false;
		private bool _isUserResizing = false;
		private bool _hasUserMovedWindow = false;
		private Point _windowPosAtStartOfUserMove = default(Point);

		/// <summary>Object that describes the current modifications being made to the chrome.</summary>
		private WindowChrome _chromeInfo;

		// Keep track of this so we can detect when we need to apply changes.  Tracking these separately
		// as I've seen using just one cause things to get enough out of [....] that occasionally the caption will redraw.
		private WindowState _lastRoundingState;
		private WindowState _lastMenuState;
		private bool _isGlassEnabled;

		private WINDOWPOS _previousWP;

		#endregion

		/// <SecurityNote>
		///   Critical : Store critical methods in critical callback table
		///   Safe     : Demands full trust permissions
		/// </SecurityNote>
		[SecuritySafeCritical]
		[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
		public WindowChromeWorker()
		{
			_messageTable = new List<HANDLE_MESSAGE>
			{
				new HANDLE_MESSAGE(WM.NCUAHDRAWCAPTION,      _HandleNCUAHDrawCaption),
				new HANDLE_MESSAGE(WM.SETTEXT,               _HandleSetTextOrIcon),
				new HANDLE_MESSAGE(WM.SETICON,               _HandleSetTextOrIcon),
				new HANDLE_MESSAGE(WM.SYSCOMMAND,            _HandleRestoreWindow),
				new HANDLE_MESSAGE(WM.NCACTIVATE,            _HandleNCActivate),
				new HANDLE_MESSAGE(WM.NCCALCSIZE,            _HandleNCCalcSize),
				new HANDLE_MESSAGE(WM.NCHITTEST,             _HandleNCHitTest),
				new HANDLE_MESSAGE(WM.NCRBUTTONUP,           _HandleNCRButtonUp),
				new HANDLE_MESSAGE(WM.SIZE,                  _HandleSize),
				new HANDLE_MESSAGE(WM.WINDOWPOSCHANGING,     _HandleWindowPosChanging),
				new HANDLE_MESSAGE(WM.WINDOWPOSCHANGED,      _HandleWindowPosChanged),
				new HANDLE_MESSAGE(WM.GETMINMAXINFO,         _HandleGetMinMaxInfo),
				new HANDLE_MESSAGE(WM.DWMCOMPOSITIONCHANGED, _HandleDwmCompositionChanged),
				new HANDLE_MESSAGE(WM.ENTERSIZEMOVE,         _HandleEnterSizeMoveForAnimation),
				new HANDLE_MESSAGE(WM.MOVE,                  _HandleMoveForRealSize),
				new HANDLE_MESSAGE(WM.EXITSIZEMOVE,          _HandleExitSizeMoveForAnimation),
			};

			if (IsPresentationFrameworkVersionLessThan4)
			{
				_messageTable.AddRange(new[]
				{
				   new HANDLE_MESSAGE(WM.SETTINGCHANGE,         _HandleSettingChange),
				   new HANDLE_MESSAGE(WM.ENTERSIZEMOVE,         _HandleEnterSizeMove),
				   new HANDLE_MESSAGE(WM.EXITSIZEMOVE,          _HandleExitSizeMove),
				   new HANDLE_MESSAGE(WM.MOVE,                  _HandleMove),
				});
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		///   Safe     : Demands full trust permissions
		/// </SecurityNote>
		[SecuritySafeCritical]
		[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
		public void SetWindowChrome(WindowChrome newChrome)
		{
			VerifyAccess();
			Assert.IsNotNull(_window);

			if (newChrome == _chromeInfo)
			{
				// Nothing's changed.
				return;
			}

			if (_chromeInfo != null)
			{
				_chromeInfo.PropertyChangedThatRequiresRepaint -= _OnChromePropertyChangedThatRequiresRepaint;
			}

			_chromeInfo = newChrome;
			if (_chromeInfo != null)
			{
				_chromeInfo.PropertyChangedThatRequiresRepaint += _OnChromePropertyChangedThatRequiresRepaint;
			}

			_ApplyNewCustomChrome();
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		///   Safe     : Demands full trust permissions
		/// </SecurityNote>
		[SecuritySafeCritical]
		[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
		private void _OnChromePropertyChangedThatRequiresRepaint(object sender, EventArgs e)
		{
			_UpdateFrameState(true);
		}

		public static readonly DependencyProperty WindowChromeWorkerProperty = DependencyProperty.RegisterAttached(
			"WindowChromeWorker",
			typeof(WindowChromeWorker),
			typeof(WindowChromeWorker),
			new PropertyMetadata(null, _OnChromeWorkerChanged));

		/// <SecurityNote>
		///   Critical : Calls critical methods
		///   Safe     : Demands full trust permissions
		/// </SecurityNote>
		[SecuritySafeCritical]
		[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
		private static void _OnChromeWorkerChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
		{
			var w = (Window)d;
			var cw = (WindowChromeWorker)e.NewValue;

			// The WindowChromeWorker object should only be set on the window once, and never to null.
			Assert.IsNotNull(w);
			Assert.IsNotNull(cw);
			Assert.IsNull(cw._window);

			cw._SetWindow(w);
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _SetWindow(Window window)
		{
			Assert.IsNull(_window);
			Assert.IsNotNull(window);

			UnsubscribeWindowEvents();

			_window = window;

			// There are potentially a couple funny states here.
			// The window may have been shown and closed, in which case it's no longer usable.
			// We shouldn't add any hooks in that case, just exit early.
			// If the window hasn't yet been shown, then we need to make sure to remove hooks after it's closed.
			_hwnd = new WindowInteropHelper(_window).Handle;

			// On older versions of the framework the client size of the window is incorrectly calculated.
			// We need to modify the template to fix this on behalf of the user.

			// This should only be required on older versions of the framework, but because of a DWM bug in Windows 7 we're exposing
			// the SacrificialEdge property which requires this kind of fixup to be a bit more ubiquitous.
			Utility.AddDependencyPropertyChangeListener(_window, Window.TemplateProperty, _OnWindowPropertyChangedThatRequiresTemplateFixup);
			Utility.AddDependencyPropertyChangeListener(_window, Window.FlowDirectionProperty, _OnWindowPropertyChangedThatRequiresTemplateFixup);

			_window.Closed += _UnsetWindow;

			// Use whether we can get an HWND to determine if the Window has been loaded.
			if (IntPtr.Zero != _hwnd)
			{
				// We've seen that the HwndSource can't always be retrieved from the HWND, so cache it early.
				// Specifically it seems to sometimes disappear when the OS theme is changing.
				_hwndSource = HwndSource.FromHwnd(_hwnd);
				Assert.IsNotNull(_hwndSource);
				_window.ApplyTemplate();

				if (_chromeInfo != null)
				{
					_ApplyNewCustomChrome();
				}
			}
			else
			{
				_window.SourceInitialized += _WindowSourceInitialized;
			}
		}

		/// <SecurityNote>
		///   Critical : Store critical methods in critical callback table
		///   Safe     : Demands full trust permissions
		/// </SecurityNote>
		[SecuritySafeCritical]
		[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
		private void _WindowSourceInitialized(object sender, EventArgs e)
		{
			_hwnd = new WindowInteropHelper(_window).Handle;
			Assert.IsNotDefault(_hwnd);
			_hwndSource = HwndSource.FromHwnd(_hwnd);
			Assert.IsNotNull(_hwndSource);

			if (_chromeInfo != null)
			{
				_ApplyNewCustomChrome();
			}
		}

		/// <SecurityNote>
		///   Critical : References critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void UnsubscribeWindowEvents()
		{
			if (_window != null)
			{
				Utility.RemoveDependencyPropertyChangeListener(_window, Window.TemplateProperty, _OnWindowPropertyChangedThatRequiresTemplateFixup);
				Utility.RemoveDependencyPropertyChangeListener(_window, Window.FlowDirectionProperty, _OnWindowPropertyChangedThatRequiresTemplateFixup);
				_window.SourceInitialized -= _WindowSourceInitialized;
				_window.StateChanged -= _FixupRestoreBounds;
			}
		}

		/// <SecurityNote>
		///   Critical : Store critical methods in critical callback table
		///   Safe     : Demands full trust permissions
		/// </SecurityNote>
		[SecuritySafeCritical]
		[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
		private void _UnsetWindow(object sender, EventArgs e)
		{
			UnsubscribeWindowEvents();

			if (_chromeInfo != null)
			{
				_chromeInfo.PropertyChangedThatRequiresRepaint -= _OnChromePropertyChangedThatRequiresRepaint;
			}

			_RestoreStandardChromeState(true);
		}

		[SuppressMessage("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters")]
		public static WindowChromeWorker GetWindowChromeWorker(Window window)
		{
			Verify.IsNotNull(window, "window");
			return (WindowChromeWorker)window.GetValue(WindowChromeWorkerProperty);
		}

		[SuppressMessage("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters")]
		public static void SetWindowChromeWorker(Window window, WindowChromeWorker chrome)
		{
			Verify.IsNotNull(window, "window");
			window.SetValue(WindowChromeWorkerProperty, chrome);
		}

		/// <SecurityNote>
		///   Critical : Accesses critical _hwnd field
		///   Safe     : Demands full trust permissions
		/// </SecurityNote>
		[SecuritySafeCritical]
		[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
		private void _OnWindowPropertyChangedThatRequiresTemplateFixup(object sender, EventArgs e)
		{
			if (_chromeInfo != null && _hwnd != IntPtr.Zero)
			{
				// Assume that when the template changes it's going to be applied.
				// We don't have a good way to externally hook into the template
				// actually being applied, so we asynchronously post the fixup operation
				// at Loaded priority, so it's expected that the visual tree will be
				// updated before _FixupTemplateIssues is called.
				_window.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, (_Action)_FixupTemplateIssues);
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _ApplyNewCustomChrome()
		{
			if (_hwnd == IntPtr.Zero || _hwndSource.IsDisposed)
			{
				// Not yet hooked.
				return;
			}

			if (_chromeInfo == null)
			{
				_RestoreStandardChromeState(false);
				return;
			}

			if (!_isHooked)
			{
				_hwndSource.AddHook(_WndProc);
				_isHooked = true;
			}

			if (_MinimizeAnimation)
			{
				// allow animation
				_ModifyStyle(0, WS.CAPTION);
			}

			_FixupTemplateIssues();

			// Force this the first time.
			_UpdateSystemMenu(_window.WindowState);
			_UpdateFrameState(true);

			NativeMethods.SetWindowPos(_hwnd, IntPtr.Zero, 0, 0, 0, 0, _SwpFlags);
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _FixupTemplateIssues()
		{
			Assert.IsNotNull(_chromeInfo);
			Assert.IsNotNull(_window);

			if (_window.Template == null)
			{
				// Nothing to fixup yet.  This will get called again when a template does get set.
				return;
			}

			// Guard against the visual tree being empty.
			if (VisualTreeHelper.GetChildrenCount(_window) == 0)
			{
				// The template isn't null, but we don't have a visual tree.
				// Hope that ApplyTemplate is in the queue and repost this, because there's not much we can do right now.
				_window.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, (_Action)_FixupTemplateIssues);
				return;
			}

			Thickness templateFixupMargin = default(Thickness);
			Transform templateFixupTransform = null;

			var rootElement = (FrameworkElement)VisualTreeHelper.GetChild(_window, 0);

			if (_chromeInfo.SacrificialEdge != SacrificialEdge.None)
			{
				if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Top))
				{
					templateFixupMargin.Top -= SystemParameters2.Current.WindowResizeBorderThickness.Top;
				}
				if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Left))
				{
					templateFixupMargin.Left -= SystemParameters2.Current.WindowResizeBorderThickness.Left;
				}
				if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Bottom))
				{
					templateFixupMargin.Bottom -= SystemParameters2.Current.WindowResizeBorderThickness.Bottom;
				}
				if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Right))
				{
					templateFixupMargin.Right -= SystemParameters2.Current.WindowResizeBorderThickness.Right;
				}
			}

			if (IsPresentationFrameworkVersionLessThan4)
			{
				RECT rcWindow = NativeMethods.GetWindowRect(_hwnd);
				RECT rcAdjustedClient = _GetAdjustedWindowRect(rcWindow);

				Rect rcLogicalWindow = DpiHelper.DeviceRectToLogical(new Rect(rcWindow.Left, rcWindow.Top, rcWindow.Width, rcWindow.Height));
				Rect rcLogicalClient = DpiHelper.DeviceRectToLogical(new Rect(rcAdjustedClient.Left, rcAdjustedClient.Top, rcAdjustedClient.Width, rcAdjustedClient.Height));

				if (!Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Left))
				{
					templateFixupMargin.Right -= SystemParameters2.Current.WindowResizeBorderThickness.Left;
				}

				if (!Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Right))
				{
					templateFixupMargin.Right -= SystemParameters2.Current.WindowResizeBorderThickness.Right;
				}

				if (!Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Top))
				{
					templateFixupMargin.Bottom -= SystemParameters2.Current.WindowResizeBorderThickness.Top;
				}

				if (!Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Bottom))
				{
					templateFixupMargin.Bottom -= SystemParameters2.Current.WindowResizeBorderThickness.Bottom;
				}

				templateFixupMargin.Bottom -= SystemParameters2.Current.WindowCaptionHeight;

				// The negative thickness on the margin doesn't properly get applied in RTL layouts.
				// The width is right, but there is a black bar on the right.
				// To fix this we just add an additional RenderTransform to the root element.
				// This works fine, but if the window is dynamically changing its FlowDirection then this can have really bizarre side effects.
				// This will mostly work if the FlowDirection is dynamically changed, but there aren't many real scenarios that would call for
				// that so I'm not addressing the rest of the quirkiness.
				if (_window.FlowDirection == FlowDirection.RightToLeft)
				{
					Thickness nonClientThickness = new Thickness(
					   rcLogicalWindow.Left - rcLogicalClient.Left,
					   rcLogicalWindow.Top - rcLogicalClient.Top,
					   rcLogicalClient.Right - rcLogicalWindow.Right,
					   rcLogicalClient.Bottom - rcLogicalWindow.Bottom);

					templateFixupTransform = new MatrixTransform(1, 0, 0, 1, -(nonClientThickness.Left + nonClientThickness.Right), 0);
				}
				else
				{
					templateFixupTransform = null;
				}

				rootElement.RenderTransform = templateFixupTransform;
			}

			rootElement.Margin = templateFixupMargin;

			if (IsPresentationFrameworkVersionLessThan4)
			{
				if (!_isFixedUp)
				{
					_hasUserMovedWindow = false;
					_window.StateChanged += _FixupRestoreBounds;

					_isFixedUp = true;
				}
			}
		}

		/// <SecurityNote>
		///   Critical : Store critical methods in critical callback table
		///   Safe     : Demands full trust permissions
		/// </SecurityNote>
		[SecuritySafeCritical]
		[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
		private void _FixupRestoreBounds(object sender, EventArgs e)
		{
			Assert.IsTrue(IsPresentationFrameworkVersionLessThan4);
			if (_window.WindowState == WindowState.Maximized || _window.WindowState == WindowState.Minimized)
			{
				// Old versions of WPF sometimes force their incorrect idea of the Window's location
				// on the Win32 restore bounds.  If we have reason to think this is the case, then
				// try to undo what WPF did after it has done its thing.
				if (_hasUserMovedWindow)
				{
					_hasUserMovedWindow = false;
					WINDOWPLACEMENT wp = NativeMethods.GetWindowPlacement(_hwnd);

					RECT adjustedDeviceRc = _GetAdjustedWindowRect(new RECT { Bottom = 100, Right = 100 });
					Point adjustedTopLeft = DpiHelper.DevicePixelsToLogical(
						new Point(
							wp.rcNormalPosition.Left - adjustedDeviceRc.Left,
							wp.rcNormalPosition.Top - adjustedDeviceRc.Top));

					_window.Top = adjustedTopLeft.Y;
					_window.Left = adjustedTopLeft.X;
				}
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private RECT _GetAdjustedWindowRect(RECT rcWindow)
		{
			// This should only be used to work around issues in the Framework that were fixed in 4.0
			Assert.IsTrue(IsPresentationFrameworkVersionLessThan4);

			var style = (WS)NativeMethods.GetWindowLongPtr(_hwnd, GWL.STYLE);
			var exstyle = (WS_EX)NativeMethods.GetWindowLongPtr(_hwnd, GWL.EXSTYLE);

			return NativeMethods.AdjustWindowRectEx(rcWindow, style, false, exstyle);
		}

		// Windows tries hard to hide this state from applications.
		// Generally you can tell that the window is in a docked position because the restore bounds from GetWindowPlacement
		// don't match the current window location and it's not in a maximized or minimized state.
		// Because this isn't doced or supported, it's also not incredibly consistent.  Sometimes some things get updated in
		// different orders, so this isn't absolutely reliable.
		/// <SecurityNote>
		///   Critical : Calls critical method
		/// </SecurityNote>
		private bool _IsWindowDocked
		{
			[SecurityCritical]
			get
			{
				// We're only detecting this state to work around .Net 3.5 issues.
				// This logic won't work correctly when those issues are fixed.
				Assert.IsTrue(IsPresentationFrameworkVersionLessThan4);

				if (_window.WindowState != WindowState.Normal)
				{
					return false;
				}

				RECT adjustedOffset = _GetAdjustedWindowRect(new RECT { Bottom = 100, Right = 100 });
				Point windowTopLeft = new Point(_window.Left, _window.Top);
				windowTopLeft -= (Vector)DpiHelper.DevicePixelsToLogical(new Point(adjustedOffset.Left, adjustedOffset.Top));

				return _window.RestoreBounds.Location != windowTopLeft;
			}
		}

		/// A borderless window lost his animation, with this we bring it back.
		private bool _MinimizeAnimation
		{
			get
			{
				return SystemParameters.MinimizeAnimation && _chromeInfo.IgnoreTaskbarOnMaximize == false;// && _chromeInfo.UseNoneWindowStyle == false;
			}
		}

		#region WindowProc and Message Handlers

		/// <SecurityNote>
		///   Critical : Accesses critical _hwnd
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
		{
			// Only expecting messages for our cached HWND.
			Assert.AreEqual(hwnd, _hwnd);

			// Check if window has a RootVisual to workaround issue #13 (Win32Exception on closing window).
			// RootVisual gets cleared when the window is closing. This happens in CloseWindowFromWmClose of the Window class.
			if (_hwndSource?.RootVisual == null)
			{
				return IntPtr.Zero;
			}

			var message = (WM)msg;
			foreach (var handlePair in _messageTable)
			{
				if (handlePair.Key == message)
				{
					return handlePair.Value(message, wParam, lParam, out handled);
				}
			}
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleNCUAHDrawCaption(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			if (false == _window.ShowInTaskbar && _GetHwndState() == WindowState.Minimized)
			{
				bool modified = _ModifyStyle(WS.VISIBLE, 0);

				// Minimize the window with ShowInTaskbar == false cause Windows to redraw the caption.
				// Letting the default WndProc handle the message without the WS_VISIBLE
				// style applied bypasses the redraw.
				IntPtr lRet = NativeMethods.DefWindowProc(_hwnd, uMsg, wParam, lParam);

				// Put back the style we removed.
				if (modified)
				{
					_ModifyStyle(0, WS.VISIBLE);
				}
				handled = true;
				return lRet;
			}
			else
			{
				handled = false;
				return IntPtr.Zero;
			}
		}

		private IntPtr _HandleSetTextOrIcon(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			bool modified = _ModifyStyle(WS.VISIBLE, 0);

			// Setting the caption text and icon cause Windows to redraw the caption.
			// Letting the default WndProc handle the message without the WS_VISIBLE
			// style applied bypasses the redraw.
			IntPtr lRet = NativeMethods.DefWindowProc(_hwnd, uMsg, wParam, lParam);

			// Put back the style we removed.
			if (modified)
			{
				_ModifyStyle(0, WS.VISIBLE);
			}
			handled = true;
			return lRet;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleRestoreWindow(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			WINDOWPLACEMENT wpl = NativeMethods.GetWindowPlacement(_hwnd);
			var sc = (SC)(Environment.Is64BitProcess ? wParam.ToInt64() : wParam.ToInt32());
			if (SC.RESTORE == sc && wpl.showCmd == SW.SHOWMAXIMIZED && _MinimizeAnimation)
			{
				var modified = _ModifyStyle(WS.SYSMENU, 0);

				IntPtr lRet = NativeMethods.DefWindowProc(_hwnd, uMsg, wParam, lParam);

				// Put back the style we removed.
				if (modified)
				{
					modified = _ModifyStyle(0, WS.SYSMENU);
				}
				handled = true;
				return lRet;
			}
			else
			{
				handled = false;
				return IntPtr.Zero;
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleNCActivate(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			// Despite MSDN's documentation of lParam not being used,
			// calling DefWindowProc with lParam set to -1 causes Windows not to draw over the caption.

			// Directly call DefWindowProc with a custom parameter
			// which bypasses any other handling of the message.
			IntPtr lRet = NativeMethods.DefWindowProc(_hwnd, WM.NCACTIVATE, wParam, new IntPtr(-1));
			handled = true;
			return lRet;
		}

		/// <summary>
		/// This method handles the window size if the taskbar is set to auto-hide.
		/// </summary>
		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private static RECT AdjustWorkingAreaForAutoHide(IntPtr monitorContainingApplication, RECT area)
		{
			// maybe we can use ReBarWindow32 isntead Shell_TrayWnd
			IntPtr hwnd = NativeMethods.FindWindow("Shell_TrayWnd", null);
			IntPtr monitorWithTaskbarOnIt = NativeMethods.MonitorFromWindow(hwnd, (uint)MonitorOptions.MONITOR_DEFAULTTONEAREST);

			var abd = new APPBARDATA();
			abd.cbSize = Marshal.SizeOf(abd);
			abd.hWnd = hwnd;
			NativeMethods.SHAppBarMessage((int)ABMsg.ABM_GETTASKBARPOS, ref abd);
			bool autoHide = Convert.ToBoolean(NativeMethods.SHAppBarMessage((int)ABMsg.ABM_GETSTATE, ref abd));

			if (!autoHide || !Equals(monitorContainingApplication, monitorWithTaskbarOnIt))
			{
				return area;
			}

			switch (abd.uEdge)
			{
				case (int)ABEdge.ABE_LEFT:
					area.Left += 2;
					break;
				case (int)ABEdge.ABE_RIGHT:
					area.Right -= 2;
					break;
				case (int)ABEdge.ABE_TOP:
					area.Top += 2;
					break;
				case (int)ABEdge.ABE_BOTTOM:
					area.Bottom -= 2;
					break;
				default:
					return area;
			}
			return area;
		}

		// Black Border Workaround
		//
		// 762437 - DWM: Windows that have both clip and alpha margins are drawn without respecting alpha
		// There was a regression in DWM in Windows 7 with regard to handling WM_NCCALCSIZE to effect custom chrome.
		// When windows with glass are maximized on a multi-monitor setup, the glass frame tends to turn black.
		// Also, when windows are resized they tend to flicker black, sometimes staying that way until resized again.
		//
		// At least on RTM Win7 we can avoid the problem by making the client area not extactly match the non-client
		// area, so we added the SacrificialEdge property.
		/// <SecurityNote>
		///   Critical : Calls critical Marshal.PtrToStructure
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleNCCalcSize(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			// lParam is an [in, out] that can be either a RECT* (wParam == FALSE) or an NCCALCSIZE_PARAMS*.
			// Since the first field of NCCALCSIZE_PARAMS is a RECT and is the only field we care about
			// we can unconditionally treat it as a RECT.

			if (NativeMethods.GetWindowPlacement(_hwnd).showCmd == SW.MAXIMIZE)
			{
				if (_MinimizeAnimation)
				{
					IntPtr mon = NativeMethods.MonitorFromWindow(_hwnd, (uint)MonitorOptions.MONITOR_DEFAULTTONEAREST);
					MONITORINFO mi = NativeMethods.GetMonitorInfo(mon);

					RECT rc = (RECT)Marshal.PtrToStructure(lParam, typeof(RECT));
					NativeMethods.DefWindowProc(_hwnd, WM.NCCALCSIZE, wParam, lParam);
					RECT def = (RECT)Marshal.PtrToStructure(lParam, typeof(RECT));
					def.Top = (int)(rc.Top + NativeMethods.GetWindowInfo(_hwnd).cyWindowBorders);

					// monitor an work area will be equal if taskbar is hidden
					if (mi.rcMonitor.Height == mi.rcWork.Height && mi.rcMonitor.Width == mi.rcWork.Width)
					{
						def = AdjustWorkingAreaForAutoHide(mon, def);
					}
					Marshal.StructureToPtr(def, lParam, true);
				}
			}

			if (_chromeInfo.SacrificialEdge != SacrificialEdge.None)
			{
				Thickness windowResizeBorderThicknessDevice = DpiHelper.LogicalThicknessToDevice(SystemParameters2.Current.WindowResizeBorderThickness);

				var rcClientArea = (RECT)Marshal.PtrToStructure(lParam, typeof(RECT));
				if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Top))
				{
					rcClientArea.Top += (int)windowResizeBorderThicknessDevice.Top;
				}
				if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Left))
				{
					rcClientArea.Left += (int)windowResizeBorderThicknessDevice.Left;
				}
				if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Bottom))
				{
					rcClientArea.Bottom -= (int)windowResizeBorderThicknessDevice.Bottom;
				}
				if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Right))
				{
					rcClientArea.Right -= (int)windowResizeBorderThicknessDevice.Right;
				}

				Marshal.StructureToPtr(rcClientArea, lParam, false);
			}

			handled = true;

			// Using the combination of WVR.VALIDRECTS and WVR.REDRAW gives the smoothest
			// resize behavior we can achieve here.
			return new IntPtr((int)(WVR.VALIDRECTS | WVR.REDRAW));
		}

		private HT _GetHTFromResizeGripDirection(ResizeGripDirection direction)
		{
			bool compliment = _window.FlowDirection == FlowDirection.RightToLeft;
			switch (direction)
			{
				case ResizeGripDirection.Bottom:
					return HT.BOTTOM;
				case ResizeGripDirection.BottomLeft:
					return compliment ? HT.BOTTOMRIGHT : HT.BOTTOMLEFT;
				case ResizeGripDirection.BottomRight:
					return compliment ? HT.BOTTOMLEFT : HT.BOTTOMRIGHT;
				case ResizeGripDirection.Left:
					return compliment ? HT.RIGHT : HT.LEFT;
				case ResizeGripDirection.Right:
					return compliment ? HT.LEFT : HT.RIGHT;
				case ResizeGripDirection.Top:
					return HT.TOP;
				case ResizeGripDirection.TopLeft:
					return compliment ? HT.TOPRIGHT : HT.TOPLEFT;
				case ResizeGripDirection.TopRight:
					return compliment ? HT.TOPLEFT : HT.TOPRIGHT;
				case ResizeGripDirection.Caption:
					return HT.CAPTION;
				default:
					return HT.NOWHERE;
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleNCHitTest(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			// Let the system know if we consider the mouse to be in our effective non-client area.
			var mousePosScreen = Utility.GetPoint(lParam); //new Point(Utility.GET_X_LPARAM(lParam), Utility.GET_Y_LPARAM(lParam));
			Rect windowPosition = _GetWindowRect();

			Point mousePosWindow = mousePosScreen;
			mousePosWindow.Offset(-windowPosition.X, -windowPosition.Y);
			mousePosWindow = DpiHelper.DevicePixelsToLogical(mousePosWindow);

			// If the app is asking for content to be treated as client then that takes precedence over _everything_, even DWM caption buttons.
			// This allows apps to set the glass frame to be non-empty, still cover it with WPF content to hide all the glass,
			// yet still get DWM to draw a drop shadow.
			IInputElement inputElement = _window.InputHitTest(mousePosWindow);
			if (inputElement != null)
			{
				if (WindowChrome.GetIsHitTestVisibleInChrome(inputElement))
				{
					handled = true;
					return new IntPtr((int)HT.CLIENT);
				}

				ResizeGripDirection direction = WindowChrome.GetResizeGripDirection(inputElement);
				if (direction != ResizeGripDirection.None)
				{
					handled = true;
					return new IntPtr((int)_GetHTFromResizeGripDirection(direction));
				}
			}

			// It's not opted out, so offer up the hittest to DWM, then to our custom non-client area logic.
			if (_chromeInfo.UseAeroCaptionButtons)
			{
				IntPtr lRet;
				if (Utility.IsOSVistaOrNewer && _chromeInfo.GlassFrameThickness != default(Thickness) && _isGlassEnabled)
				{
					// If we're on Vista, give the DWM a chance to handle the message first.
					handled = NativeMethods.DwmDefWindowProc(_hwnd, uMsg, wParam, lParam, out lRet);

					if (IntPtr.Zero != lRet)
					{
						// If DWM claims to have handled this, then respect their call.
						return lRet;
					}
				}
			}

			HT ht = _HitTestNca(
				DpiHelper.DeviceRectToLogical(windowPosition),
				DpiHelper.DevicePixelsToLogical(mousePosScreen));

			handled = true;
			return new IntPtr((int)ht);
		}

		/// <SecurityNote>
		///   Critical : Calls critical method
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleNCRButtonUp(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			// Emulate the system behavior of clicking the right mouse button over the caption area
			// to bring up the system menu.
			if (HT.CAPTION == (HT)(Environment.Is64BitProcess ? wParam.ToInt64() : wParam.ToInt32()))
			{
				//SystemCommands.ShowSystemMenuPhysicalCoordinates(_window, new Point(Utility.GET_X_LPARAM(lParam), Utility.GET_Y_LPARAM(lParam)));
				SystemCommands.ShowSystemMenuPhysicalCoordinates(_window, Utility.GetPoint(lParam));
			}
			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical method
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleSize(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			const int SIZE_MAXIMIZED = 2;

			// Force when maximized.
			// We can tell what's happening right now, but the Window doesn't yet know it's
			// maximized.  Not forcing this update will eventually cause the
			// default caption to be drawn.
			WindowState? state = null;
			if ((Environment.Is64BitProcess ? wParam.ToInt64() : wParam.ToInt32()) == SIZE_MAXIMIZED)
			{
				state = WindowState.Maximized;
			}
			_UpdateSystemMenu(state);

			// Still let the default WndProc handle this.
			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical Marshal.PtrToStructure
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleWindowPosChanging(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			if (!_isGlassEnabled)
			{
				Assert.IsNotDefault(lParam);
				var wp = (WINDOWPOS)Marshal.PtrToStructure(lParam, typeof(WINDOWPOS));

				// we don't do bitwise operations cuz we're checking for this flag being the only one there
				// I have no clue why this works, I tried this because VS2013 has this flag removed on fullscreen window movws
				if (_chromeInfo.IgnoreTaskbarOnMaximize && _GetHwndState() == WindowState.Maximized && wp.flags == (int)SWP.FRAMECHANGED)
				{
					wp.flags = 0;
					Marshal.StructureToPtr(wp, lParam, true);
				}
			}

			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical Marshal.PtrToStructure
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleWindowPosChanged(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			// http://blogs.msdn.com/oldnewthing/archive/2008/01/15/7113860.aspx
			// The WM_WINDOWPOSCHANGED message is sent at the end of the window
			// state change process. It sort of combines the other state change
			// notifications, WM_MOVE, WM_SIZE, and WM_SHOWWINDOW. But it doesn't
			// suffer from the same limitations as WM_SHOWWINDOW, so you can
			// reliably use it to react to the window being shown or hidden.

			_UpdateSystemMenu(null);

			if (!_isGlassEnabled)
			{
				Assert.IsNotDefault(lParam);
				var wp = (WINDOWPOS)Marshal.PtrToStructure(lParam, typeof(WINDOWPOS));

				if (!wp.Equals(_previousWP))
				{
					_previousWP = wp;
					_SetRoundingRegion(wp);
				}
				_previousWP = wp;

				//                if (wp.Equals(_previousWP) && wp.flags.Equals(_previousWP.flags))
				//                {
				//                    handled = true;
				//                    return IntPtr.Zero;
				//                }
			}

			// Still want to pass this to DefWndProc
			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleGetMinMaxInfo(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			/*
             * This is a workaround for wrong windows behaviour.
             * If a Window sets the WindoStyle to None and WindowState to maximized and we have a multi monitor system
             * we can move the Window only one time. After that it's not possible to move the Window back to the
             * previous monitor.
             * This fix is not really a full fix. Moving the Window back gives us the wrong size, because
             * MonitorFromWindow gives us the wrong (old) monitor! This is fixed in _HandleMoveForRealSize.
             */
			var ignoreTaskBar = _chromeInfo.IgnoreTaskbarOnMaximize;// || _chromeInfo.UseNoneWindowStyle;
			if (ignoreTaskBar && NativeMethods.IsZoomed(_hwnd))
			{
				MINMAXINFO mmi = (MINMAXINFO)Marshal.PtrToStructure(lParam, typeof(MINMAXINFO));
				IntPtr monitor = NativeMethods.MonitorFromWindow(_hwnd, (uint)MonitorOptions.MONITOR_DEFAULTTONEAREST);
				if (monitor != IntPtr.Zero)
				{
					MONITORINFO monitorInfo = NativeMethods.GetMonitorInfoW(monitor);
					RECT rcWorkArea = monitorInfo.rcWork;
					RECT rcMonitorArea = monitorInfo.rcMonitor;

					mmi.ptMaxPosition.x = Math.Abs(rcWorkArea.Left - rcMonitorArea.Left);
					mmi.ptMaxPosition.y = Math.Abs(rcWorkArea.Top - rcMonitorArea.Top);

					mmi.ptMaxSize.x = Math.Abs(monitorInfo.rcMonitor.Width);
					mmi.ptMaxSize.y = Math.Abs(monitorInfo.rcMonitor.Height);
					mmi.ptMaxTrackSize.x = mmi.ptMaxSize.x;
					mmi.ptMaxTrackSize.y = mmi.ptMaxSize.y;
				}
				Marshal.StructureToPtr(mmi, lParam, true);
			}

			/* Setting handled to false enables the application to process it's own Min/Max requirements,
             * as mentioned by jason.bullard (comment from September 22, 2011) on http://gallery.expression.microsoft.com/ZuneWindowBehavior/ */
			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleDwmCompositionChanged(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			_UpdateFrameState(false);

			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleSettingChange(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			// There are several settings that can cause fixups for the template to become invalid when changed.
			// These shouldn't be required on the v4 framework.
			Assert.IsTrue(IsPresentationFrameworkVersionLessThan4);

			_FixupTemplateIssues();

			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleEnterSizeMove(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			// This is only intercepted to deal with bugs in Window in .Net 3.5 and below.
			Assert.IsTrue(IsPresentationFrameworkVersionLessThan4);

			_isUserResizing = true;

			// On Win7 if the user is dragging the window out of the maximized state then we don't want to use that location
			// as a restore point.
			Assert.Implies(_window.WindowState == WindowState.Maximized, Utility.IsOSWindows7OrNewer);
			if (_window.WindowState != WindowState.Maximized)
			{
				// Check for the docked window case.  The window can still be restored when it's in this position so
				// try to account for that and not update the start position.
				if (!_IsWindowDocked)
				{
					_windowPosAtStartOfUserMove = new Point(_window.Left, _window.Top);
				}
				// Realistically we also don't want to update the start position when moving from one docked state to another (or to and from maximized),
				// but it's tricky to detect and this is already a workaround for a bug that's fixed in newer versions of the framework.
				// Not going to try to handle all cases.
			}

			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleEnterSizeMoveForAnimation(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			if (_MinimizeAnimation)// && _GetHwndState() != WindowState.Minimized)
			{
				/* we only need to remove DLGFRAME ( CAPTION = BORDER | DLGFRAME )
                 * to prevent nasty drawing
                 * removing border will cause a 1 off error on the client rect size
                 * when maximizing via aero snapping, because max by aero snapping
                 * will call this method, resulting in a 2px black border on the side
                 * when maximized.
                 */
				_ModifyStyle(WS.CAPTION, 0);
			}
			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleMoveForRealSize(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			/*
             * This is a workaround for wrong windows behaviour (with multi monitor system).
             * If a Window sets the WindoStyle to None and WindowState to maximized
             * we can move the Window to different monitor with maybe different dimension.
             * But after moving to the previous monitor we got a wrong size (from the old monitor dimension).
             */
			WindowState state = _GetHwndState();
			if (state == WindowState.Maximized)
			{
				IntPtr monitorFromWindow = NativeMethods.MonitorFromWindow(_hwnd, (uint)MonitorOptions.MONITOR_DEFAULTTONEAREST);
				if (monitorFromWindow != IntPtr.Zero)
				{
					var ignoreTaskBar = _chromeInfo.IgnoreTaskbarOnMaximize;// || _chromeInfo.UseNoneWindowStyle;
					MONITORINFO monitorInfo = NativeMethods.GetMonitorInfoW(monitorFromWindow);
					RECT rcMonitorArea = ignoreTaskBar ? monitorInfo.rcMonitor : monitorInfo.rcWork;
					/*
                     * ASYNCWINDOWPOS
                     * If the calling thread and the thread that owns the window are attached to different input queues,
                     * the system posts the request to the thread that owns the window. This prevents the calling thread
                     * from blocking its execution while other threads process the request.
                     * 
                     * FRAMECHANGED
                     * Applies new frame styles set using the SetWindowLong function. Sends a WM_NCCALCSIZE message to the window,
                     * even if the window's size is not being changed. If this flag is not specified, WM_NCCALCSIZE is sent only
                     * when the window's size is being changed.
                     * 
                     * NOCOPYBITS
                     * Discards the entire contents of the client area. If this flag is not specified, the valid contents of the client
                     * area are saved and copied back into the client area after the window is sized or repositioned.
                     * 
                     */
					NativeMethods.SetWindowPos(_hwnd, IntPtr.Zero, rcMonitorArea.Left, rcMonitorArea.Top, rcMonitorArea.Width, rcMonitorArea.Height, SWP.ASYNCWINDOWPOS | SWP.FRAMECHANGED | SWP.NOCOPYBITS);
				}
			}

			handled = false;
			return IntPtr.Zero;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private IntPtr _HandleExitSizeMoveForAnimation(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			if (_MinimizeAnimation)
			{
				// restore DLGFRAME
				if (_ModifyStyle(0, WS.CAPTION))
				{
					//_UpdateFrameState(true);
					NativeMethods.SetWindowPos(_hwnd, IntPtr.Zero, 0, 0, 0, 0, _SwpFlags);
				}
			}

			handled = false;
			return IntPtr.Zero;
		}

		private IntPtr _HandleExitSizeMove(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			// This is only intercepted to deal with bugs in Window in .Net 3.5 and below.
			Assert.IsTrue(IsPresentationFrameworkVersionLessThan4);

			_isUserResizing = false;

			// On Win7 the user can change the Window's state by dragging the window to the top of the monitor.
			// If they did that, then we need to try to update the restore bounds or else WPF will put the window at the maximized location (e.g. (-8,-8)).
			if (_window.WindowState == WindowState.Maximized)
			{
				Assert.IsTrue(Utility.IsOSWindows7OrNewer);
				_window.Top = _windowPosAtStartOfUserMove.Y;
				_window.Left = _windowPosAtStartOfUserMove.X;
			}

			handled = false;
			return IntPtr.Zero;
		}

		private IntPtr _HandleMove(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
		{
			// This is only intercepted to deal with bugs in Window in .Net 3.5 and below.
			Assert.IsTrue(IsPresentationFrameworkVersionLessThan4);

			if (_isUserResizing)
			{
				_hasUserMovedWindow = true;
			}

			handled = false;
			return IntPtr.Zero;
		}

		#endregion

		/// <summary>Add and remove a native WindowStyle from the HWND.</summary>
		/// <param name="removeStyle">The styles to be removed.  These can be bitwise combined.</param>
		/// <param name="addStyle">The styles to be added.  These can be bitwise combined.</param>
		/// <returns>Whether the styles of the HWND were modified as a result of this call.</returns>
		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private bool _ModifyStyle(WS removeStyle, WS addStyle)
		{
			Assert.IsNotDefault(_hwnd);
			var intPtr = NativeMethods.GetWindowLongPtr(_hwnd, GWL.STYLE);
			var dwStyle = (WS)(Environment.Is64BitProcess ? intPtr.ToInt64() : intPtr.ToInt32());
			var dwNewStyle = (dwStyle & ~removeStyle) | addStyle;
			if (dwStyle == dwNewStyle)
			{
				return false;
			}

			NativeMethods.SetWindowLongPtr(_hwnd, GWL.STYLE, new IntPtr((int)dwNewStyle));
			return true;
		}

		/// <summary>
		/// Get the WindowState as the native HWND knows it to be.  This isn't necessarily the same as what Window thinks.
		/// </summary>
		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private WindowState _GetHwndState()
		{
			var wpl = NativeMethods.GetWindowPlacement(_hwnd);
			switch (wpl.showCmd)
			{
				case SW.SHOWMINIMIZED:
					return WindowState.Minimized;
				case SW.SHOWMAXIMIZED:
					return WindowState.Maximized;
			}
			return WindowState.Normal;
		}

		/// <summary>
		/// Get the bounding rectangle for the window in physical coordinates.
		/// </summary>
		/// <returns>The bounding rectangle for the window.</returns>
		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private Rect _GetWindowRect()
		{
			// Get the window rectangle.
			RECT windowPosition = NativeMethods.GetWindowRect(_hwnd);
			return new Rect(windowPosition.Left, windowPosition.Top, windowPosition.Width, windowPosition.Height);
		}

		/// <summary>
		/// Update the items in the system menu based on the current, or assumed, WindowState.
		/// </summary>
		/// <param name="assumeState">
		/// The state to assume that the Window is in.  This can be null to query the Window's state.
		/// </param>
		/// <remarks>
		/// We want to update the menu while we have some control over whether the caption will be repainted.
		/// </remarks>
		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _UpdateSystemMenu(WindowState? assumeState)
		{
			const MF mfEnabled = MF.ENABLED | MF.BYCOMMAND;
			const MF mfDisabled = MF.GRAYED | MF.DISABLED | MF.BYCOMMAND;

			WindowState state = assumeState ?? _GetHwndState();

			if (null != assumeState || _lastMenuState != state)
			{
				_lastMenuState = state;

				IntPtr hmenu = NativeMethods.GetSystemMenu(_hwnd, false);
				if (IntPtr.Zero != hmenu)
				{
					var intPtr = NativeMethods.GetWindowLongPtr(_hwnd, GWL.STYLE);
					var dwStyle = (WS)(Environment.Is64BitProcess ? intPtr.ToInt64() : intPtr.ToInt32());

					bool canMinimize = Utility.IsFlagSet((int)dwStyle, (int)WS.MINIMIZEBOX);
					bool canMaximize = Utility.IsFlagSet((int)dwStyle, (int)WS.MAXIMIZEBOX);
					bool canSize = Utility.IsFlagSet((int)dwStyle, (int)WS.THICKFRAME);

					switch (state)
					{
						case WindowState.Maximized:
							NativeMethods.EnableMenuItem(hmenu, SC.RESTORE, mfEnabled);
							NativeMethods.EnableMenuItem(hmenu, SC.MOVE, mfDisabled);
							NativeMethods.EnableMenuItem(hmenu, SC.SIZE, mfDisabled);
							NativeMethods.EnableMenuItem(hmenu, SC.MINIMIZE, canMinimize ? mfEnabled : mfDisabled);
							NativeMethods.EnableMenuItem(hmenu, SC.MAXIMIZE, mfDisabled);
							break;
						case WindowState.Minimized:
							NativeMethods.EnableMenuItem(hmenu, SC.RESTORE, mfEnabled);
							NativeMethods.EnableMenuItem(hmenu, SC.MOVE, mfDisabled);
							NativeMethods.EnableMenuItem(hmenu, SC.SIZE, mfDisabled);
							NativeMethods.EnableMenuItem(hmenu, SC.MINIMIZE, mfDisabled);
							NativeMethods.EnableMenuItem(hmenu, SC.MAXIMIZE, canMaximize ? mfEnabled : mfDisabled);
							break;
						default:
							NativeMethods.EnableMenuItem(hmenu, SC.RESTORE, mfDisabled);
							NativeMethods.EnableMenuItem(hmenu, SC.MOVE, mfEnabled);
							NativeMethods.EnableMenuItem(hmenu, SC.SIZE, canSize ? mfEnabled : mfDisabled);
							NativeMethods.EnableMenuItem(hmenu, SC.MINIMIZE, canMinimize ? mfEnabled : mfDisabled);
							NativeMethods.EnableMenuItem(hmenu, SC.MAXIMIZE, canMaximize ? mfEnabled : mfDisabled);
							break;
					}
				}
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _UpdateFrameState(bool force)
		{
			if (IntPtr.Zero == _hwnd || _hwndSource.IsDisposed)
			{
				return;
			}

			// Don't rely on SystemParameters for this, just make the check ourselves.
			bool frameState = NativeMethods.DwmIsCompositionEnabled();

			if (force || frameState != _isGlassEnabled)
			{
				_isGlassEnabled = frameState && _chromeInfo.GlassFrameThickness != default(Thickness);

				if (!_isGlassEnabled)
				{
					_SetRoundingRegion(null);
				}
				else
				{
					_ClearRoundingRegion();
					_ExtendGlassFrame();
				}

				if (_MinimizeAnimation)
				{
					// allow animation
					_ModifyStyle(0, WS.CAPTION);
				}
				else
				{
					// no animation
					_ModifyStyle(WS.CAPTION, 0);
				}

				NativeMethods.SetWindowPos(_hwnd, IntPtr.Zero, 0, 0, 0, 0, _SwpFlags);
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _ClearRoundingRegion()
		{
			NativeMethods.SetWindowRgn(_hwnd, IntPtr.Zero, NativeMethods.IsWindowVisible(_hwnd));
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private RECT _GetClientRectRelativeToWindowRect(IntPtr hWnd)
		{
			RECT windowRect = NativeMethods.GetWindowRect(hWnd);
			RECT clientRect = NativeMethods.GetClientRect(hWnd);

			POINT test = new POINT() { x = 0, y = 0 };
			NativeMethods.ClientToScreen(hWnd, ref test);
			if (_window.FlowDirection == FlowDirection.RightToLeft)
			{
				clientRect.Offset(windowRect.Right - test.x, test.y - windowRect.Top);
			}
			else
			{
				clientRect.Offset(test.x - windowRect.Left, test.y - windowRect.Top);
			}
			return clientRect;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _SetRoundingRegion(WINDOWPOS? wp)
		{
			// We're early - WPF hasn't necessarily updated the state of the window.
			// Need to query it ourselves.
			WINDOWPLACEMENT wpl = NativeMethods.GetWindowPlacement(_hwnd);

			if (wpl.showCmd == SW.SHOWMAXIMIZED)
			{
				RECT rcMax;
				if (_MinimizeAnimation)
				{
					rcMax = _GetClientRectRelativeToWindowRect(_hwnd);
				}
				else
				{
					int left;
					int top;

					if (wp.HasValue)
					{
						left = wp.Value.x;
						top = wp.Value.y;
					}
					else
					{
						Rect r = _GetWindowRect();
						left = (int)r.Left;
						top = (int)r.Top;
					}

					IntPtr hMon = NativeMethods.MonitorFromWindow(_hwnd, (uint)MonitorOptions.MONITOR_DEFAULTTONEAREST);

					MONITORINFO mi = NativeMethods.GetMonitorInfo(hMon);
					rcMax = _chromeInfo.IgnoreTaskbarOnMaximize ? mi.rcMonitor : mi.rcWork;
					// The location of maximized window takes into account the border that Windows was
					// going to remove, so we also need to consider it.
					rcMax.Offset(-left, -top);
				}

				IntPtr hrgn = IntPtr.Zero;
				try
				{
					hrgn = NativeMethods.CreateRectRgnIndirect(rcMax);
					NativeMethods.SetWindowRgn(_hwnd, hrgn, NativeMethods.IsWindowVisible(_hwnd));
					hrgn = IntPtr.Zero;
				}
				finally
				{
					Utility.SafeDeleteObject(ref hrgn);
				}
			}
			else
			{
				Size windowSize;

				// Use the size if it's specified.
				if (null != wp && !Utility.IsFlagSet(wp.Value.flags, (int)SWP.NOSIZE))
				{
					windowSize = new Size((double)wp.Value.cx, (double)wp.Value.cy);
				}
				else if (null != wp && (_lastRoundingState == _window.WindowState))
				{
					return;
				}
				else
				{
					windowSize = _GetWindowRect().Size;
				}

				_lastRoundingState = _window.WindowState;

				IntPtr hrgn = IntPtr.Zero;
				try
				{
					double shortestDimension = Math.Min(windowSize.Width, windowSize.Height);

					double topLeftRadius = DpiHelper.LogicalPixelsToDevice(new Point(_chromeInfo.CornerRadius.TopLeft, 0)).X;
					topLeftRadius = Math.Min(topLeftRadius, shortestDimension / 2);

					if (_IsUniform(_chromeInfo.CornerRadius))
					{
						// RoundedRect HRGNs require an additional pixel of padding.
						hrgn = _CreateRoundRectRgn(new Rect(windowSize), topLeftRadius);
					}
					else
					{
						// We need to combine HRGNs for each of the corners.
						// Create one for each quadrant, but let it overlap into the two adjacent ones
						// by the radius amount to ensure that there aren't corners etched into the middle
						// of the window.
						hrgn = _CreateRoundRectRgn(new Rect(0, 0, windowSize.Width / 2 + topLeftRadius, windowSize.Height / 2 + topLeftRadius), topLeftRadius);

						double topRightRadius = DpiHelper.LogicalPixelsToDevice(new Point(_chromeInfo.CornerRadius.TopRight, 0)).X;
						topRightRadius = Math.Min(topRightRadius, shortestDimension / 2);
						Rect topRightRegionRect = new Rect(0, 0, windowSize.Width / 2 + topRightRadius, windowSize.Height / 2 + topRightRadius);
						topRightRegionRect.Offset(windowSize.Width / 2 - topRightRadius, 0);
						Assert.AreEqual(topRightRegionRect.Right, windowSize.Width);

						_CreateAndCombineRoundRectRgn(hrgn, topRightRegionRect, topRightRadius);

						double bottomLeftRadius = DpiHelper.LogicalPixelsToDevice(new Point(_chromeInfo.CornerRadius.BottomLeft, 0)).X;
						bottomLeftRadius = Math.Min(bottomLeftRadius, shortestDimension / 2);
						Rect bottomLeftRegionRect = new Rect(0, 0, windowSize.Width / 2 + bottomLeftRadius, windowSize.Height / 2 + bottomLeftRadius);
						bottomLeftRegionRect.Offset(0, windowSize.Height / 2 - bottomLeftRadius);
						Assert.AreEqual(bottomLeftRegionRect.Bottom, windowSize.Height);

						_CreateAndCombineRoundRectRgn(hrgn, bottomLeftRegionRect, bottomLeftRadius);

						double bottomRightRadius = DpiHelper.LogicalPixelsToDevice(new Point(_chromeInfo.CornerRadius.BottomRight, 0)).X;
						bottomRightRadius = Math.Min(bottomRightRadius, shortestDimension / 2);
						Rect bottomRightRegionRect = new Rect(0, 0, windowSize.Width / 2 + bottomRightRadius, windowSize.Height / 2 + bottomRightRadius);
						bottomRightRegionRect.Offset(windowSize.Width / 2 - bottomRightRadius, windowSize.Height / 2 - bottomRightRadius);
						Assert.AreEqual(bottomRightRegionRect.Right, windowSize.Width);
						Assert.AreEqual(bottomRightRegionRect.Bottom, windowSize.Height);

						_CreateAndCombineRoundRectRgn(hrgn, bottomRightRegionRect, bottomRightRadius);
					}

					NativeMethods.SetWindowRgn(_hwnd, hrgn, NativeMethods.IsWindowVisible(_hwnd));
					hrgn = IntPtr.Zero;
				}
				finally
				{
					// Free the memory associated with the HRGN if it wasn't assigned to the HWND.
					Utility.SafeDeleteObject(ref hrgn);
				}
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private static IntPtr _CreateRoundRectRgn(Rect region, double radius)
		{
			// Round outwards.

			if (DoubleUtilities.AreClose(0, radius))
			{
				return NativeMethods.CreateRectRgn(
					(int)Math.Floor(region.Left),
					(int)Math.Floor(region.Top),
					(int)Math.Ceiling(region.Right),
					(int)Math.Ceiling(region.Bottom));
			}

			// RoundedRect HRGNs require an additional pixel of padding on the bottom right to look correct.
			return NativeMethods.CreateRoundRectRgn(
				(int)Math.Floor(region.Left),
				(int)Math.Floor(region.Top),
				(int)Math.Ceiling(region.Right) + 1,
				(int)Math.Ceiling(region.Bottom) + 1,
				(int)Math.Ceiling(radius),
				(int)Math.Ceiling(radius));
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		[SuppressMessage("Microsoft.Naming", "CA2204:Literals should be spelled correctly", MessageId = "HRGNs")]
		private static void _CreateAndCombineRoundRectRgn(IntPtr hrgnSource, Rect region, double radius)
		{
			IntPtr hrgn = IntPtr.Zero;
			try
			{
				hrgn = _CreateRoundRectRgn(region, radius);
				CombineRgnResult result = NativeMethods.CombineRgn(hrgnSource, hrgnSource, hrgn, RGN.OR);
				if (result == CombineRgnResult.ERROR)
				{
					throw new InvalidOperationException("Unable to combine two HRGNs.");
				}
			}
			catch
			{
				Utility.SafeDeleteObject(ref hrgn);
				throw;
			}
		}

		private static bool _IsUniform(CornerRadius cornerRadius)
		{
			if (!DoubleUtilities.AreClose(cornerRadius.BottomLeft, cornerRadius.BottomRight))
			{
				return false;
			}

			if (!DoubleUtilities.AreClose(cornerRadius.TopLeft, cornerRadius.TopRight))
			{
				return false;
			}

			if (!DoubleUtilities.AreClose(cornerRadius.BottomLeft, cornerRadius.TopRight))
			{
				return false;
			}

			return true;
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _ExtendGlassFrame()
		{
			Assert.IsNotNull(_window);

			// Expect that this might be called on OSes other than Vista.
			if (!Utility.IsOSVistaOrNewer)
			{
				// Not an error.  Just not on Vista so we're not going to get glass.
				return;
			}

			if (IntPtr.Zero == _hwnd)
			{
				// Can't do anything with this call until the Window has been shown.
				return;
			}

			// Ensure standard HWND background painting when DWM isn't enabled.
			if (!NativeMethods.DwmIsCompositionEnabled())
			{
				// Apply the transparent background to the HWND for disabled DwmIsComposition too
				// but only if the window has the flag AllowsTransparency turned on
				if (_window.AllowsTransparency)
				{
					_hwndSource.CompositionTarget.BackgroundColor = Colors.Transparent;
				}
				else
				{
					_hwndSource.CompositionTarget.BackgroundColor = SystemColors.WindowColor;
				}
			}
			else
			{
				// This makes the glass visible at a Win32 level so long as nothing else is covering it.
				// The Window's Background needs to be changed independent of this.

				// Apply the transparent background to the HWND
				// but only if the window has the flag AllowsTransparency turned on
				if (_window.AllowsTransparency)
				{
					_hwndSource.CompositionTarget.BackgroundColor = Colors.Transparent;
				}

				// Thickness is going to be DIPs, need to convert to system coordinates.
				Thickness deviceGlassThickness = DpiHelper.LogicalThicknessToDevice(_chromeInfo.GlassFrameThickness);

				if (_chromeInfo.SacrificialEdge != SacrificialEdge.None)
				{
					Thickness windowResizeBorderThicknessDevice = DpiHelper.LogicalThicknessToDevice(SystemParameters2.Current.WindowResizeBorderThickness);

					if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Top))
					{
						deviceGlassThickness.Top -= windowResizeBorderThicknessDevice.Top;
						deviceGlassThickness.Top = Math.Max(0, deviceGlassThickness.Top);
					}
					if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Left))
					{
						deviceGlassThickness.Left -= windowResizeBorderThicknessDevice.Left;
						deviceGlassThickness.Left = Math.Max(0, deviceGlassThickness.Left);
					}
					if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Bottom))
					{
						deviceGlassThickness.Bottom -= windowResizeBorderThicknessDevice.Bottom;
						deviceGlassThickness.Bottom = Math.Max(0, deviceGlassThickness.Bottom);
					}
					if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Right))
					{
						deviceGlassThickness.Right -= windowResizeBorderThicknessDevice.Right;
						deviceGlassThickness.Right = Math.Max(0, deviceGlassThickness.Right);
					}
				}

				var dwmMargin = new MARGINS
				{
					// err on the side of pushing in glass an extra pixel.
					cxLeftWidth = (int)Math.Ceiling(deviceGlassThickness.Left),
					cxRightWidth = (int)Math.Ceiling(deviceGlassThickness.Right),
					cyTopHeight = (int)Math.Ceiling(deviceGlassThickness.Top),
					cyBottomHeight = (int)Math.Ceiling(deviceGlassThickness.Bottom),
				};

				NativeMethods.DwmExtendFrameIntoClientArea(_hwnd, ref dwmMargin);
			}
		}

		/// <summary>
		/// Matrix of the HT values to return when responding to NC window messages.
		/// </summary>
		[SuppressMessage("Microsoft.Performance", "CA1814:PreferJaggedArraysOverMultidimensional", MessageId = "Member")]
		private static readonly HT[,] _HitTestBorders = new[,]
		{
			{ HT.TOPLEFT,    HT.TOP,     HT.TOPRIGHT    },
			{ HT.LEFT,       HT.CLIENT,  HT.RIGHT       },
			{ HT.BOTTOMLEFT, HT.BOTTOM,  HT.BOTTOMRIGHT },
		};

		private HT _HitTestNca(Rect windowPosition, Point mousePosition)
		{
			// Determine if hit test is for resizing, default middle (1,1).
			int uRow = 1;
			int uCol = 1;
			bool onResizeBorder = false;

			// Determine if the point is at the top or bottom of the window.
			if (mousePosition.Y >= windowPosition.Top && mousePosition.Y < windowPosition.Top + _chromeInfo.ResizeBorderThickness.Top + _chromeInfo.CaptionHeight)
			{
				onResizeBorder = (mousePosition.Y < (windowPosition.Top + _chromeInfo.ResizeBorderThickness.Top));
				uRow = 0; // top (caption or resize border)
			}
			else if (mousePosition.Y < windowPosition.Bottom && mousePosition.Y >= windowPosition.Bottom - (int)_chromeInfo.ResizeBorderThickness.Bottom)
			{
				uRow = 2; // bottom
			}

			// Determine if the point is at the left or right of the window.
			if (mousePosition.X >= windowPosition.Left && mousePosition.X < windowPosition.Left + (int)_chromeInfo.ResizeBorderThickness.Left)
			{
				uCol = 0; // left side
			}
			else if (mousePosition.X < windowPosition.Right && mousePosition.X >= windowPosition.Right - _chromeInfo.ResizeBorderThickness.Right)
			{
				uCol = 2; // right side
			}

			// If the cursor is in one of the top edges by the caption bar, but below the top resize border,
			// then resize left-right rather than diagonally.
			if (uRow == 0 && uCol != 1 && !onResizeBorder)
			{
				uRow = 1;
			}

			HT ht = _HitTestBorders[uRow, uCol];

			if (ht == HT.TOP && !onResizeBorder)
			{
				ht = HT.CAPTION;
			}

			return ht;
		}

		#region Remove Custom Chrome Methods

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _RestoreStandardChromeState(bool isClosing)
		{
			VerifyAccess();

			_UnhookCustomChrome();

			if (!isClosing && !_hwndSource.IsDisposed)
			{
				_RestoreFrameworkIssueFixups();
				_RestoreGlassFrame();
				_RestoreHrgn();

				_window.InvalidateMeasure();
			}
		}

		/// <SecurityNote>
		///   Critical : Unsubscribes event handler from critical _hwndSource
		/// </SecurityNote>
		[SecurityCritical]
		private void _UnhookCustomChrome()
		{
			//Assert.IsNotDefault(_hwnd);
			Assert.IsNotNull(_window);

			if (_isHooked)
			{
				Assert.IsNotDefault(_hwnd);
				_hwndSource.RemoveHook(_WndProc);
				_isHooked = false;
			}
		}

		/// <SecurityNote>
		///   Critical : Unsubscribes critical event handler
		/// </SecurityNote>
		[SecurityCritical]
		private void _RestoreFrameworkIssueFixups()
		{
			var rootElement = (FrameworkElement)VisualTreeHelper.GetChild(_window, 0);

			// Undo anything that was done before.
			rootElement.Margin = new Thickness();

			// This margin is only necessary if the client rect is going to be calculated incorrectly by WPF.
			// This bug was fixed in V4 of the framework.
			if (IsPresentationFrameworkVersionLessThan4)
			{
				Assert.IsTrue(_isFixedUp);
				_window.StateChanged -= _FixupRestoreBounds;
				_isFixedUp = false;
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _RestoreGlassFrame()
		{
			Assert.IsNull(_chromeInfo);
			Assert.IsNotNull(_window);

			// Expect that this might be called on OSes other than Vista
			// and if the window hasn't yet been shown, then we don't need to undo anything.
			if (!Utility.IsOSVistaOrNewer || _hwnd == IntPtr.Zero)
			{
				return;
			}

			_hwndSource.CompositionTarget.BackgroundColor = SystemColors.WindowColor;

			if (NativeMethods.DwmIsCompositionEnabled())
			{
				// If glass is enabled, push it back to the normal bounds.
				var dwmMargin = new MARGINS();
				NativeMethods.DwmExtendFrameIntoClientArea(_hwnd, ref dwmMargin);
			}
		}

		/// <SecurityNote>
		///   Critical : Calls critical methods
		/// </SecurityNote>
		[SecurityCritical]
		private void _RestoreHrgn()
		{
			_ClearRoundingRegion();
			NativeMethods.SetWindowPos(_hwnd, IntPtr.Zero, 0, 0, 0, 0, _SwpFlags);
		}

		#endregion
	}
}
